Effects of Soil Moisture Deficit on Forage Quality, Digestibility, and Protein Fractionation of Kura Clover

Kura clover (Trifolium ambiguum M.B.) is a persistent rhizomatous forage legume with great potential for permanent pastures. The effects of a soil moisture deficit on forage quality, digestibility and protein fractionation of two cultivars of Kura clover (Endura and Rhizo) were investigated in this study for 1 year. The responses of alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) were also characterized. Stands of each species were field‐grown and submitted to two soil water regimes promoting soil moisture deficits and well‐watered (i.e. control) conditions. There were no interactions between species and soil water regimes. Soil moisture deficit increased acid detergent fibre (ADF) but reduced acid detergent lignin (ADL) content and consequently increased forage digestibility. It had only minor effects on protein content and fractionation. Species varied for most parameters measured. Kura clover generally had the lowest neutral detergent fibre (NDF), ADF and ADL contents, and consequently the greatest digestibility (83.9 %). Species also differed in their crude protein fractionation. Kura clover and red clover had a lower proportion of non‐protein nitrogen (NPN; A fraction) and a greater proportion of true protein (B fraction) (30.9 and 64.5 %, respectively) than alfalfa (36.4 and 57.4 %, respectively). Kura clover also had the lowest proportion (i.e. 4.7 %) of acid detergent insoluble protein (ADIP; C fraction) of all species tested. Endura Kura clover often had a higher forage quality than Rhizo. This study confirms that Kura clover produces high‐quality forage and provides the first estimates of protein fractionation in this species.